Major changes to train services have been made following a four-mile long speed restriction between Gillingham and Tisbury on the Waterloo-Exeter line.

The South of England has endured its driest July since 1936, as well as the hottest temperatures ever recorded, and the impact has now been felt on the railway.

Sections of railway built on clay-based soil, including those around Gillingham, have dried out so badly they have shrunk, leaving the track on top uneven and dangerous to run trains at full speed.

It is likely that the speed restriction will remain in place until October, as engineers must wait for the soil to regain some of its moisture before a repair can be carried out.

Train services have had to be amended as the line is single so no trains can pass each other and trains are taking double the normal length of time to run between Gillingham and Tisbury.

The full revised timetable is currently being finalised and will be published later this week.

Network Rail's Colum Cavanagh, said: "We call this problem soil moisture deficit and although we encounter issues with it most summers, this year has been absolutely unprecedented.

"We came into the hot season with our track in the best condition it's ever been in, and yet now late August the soils around Gillingham have dried so badly the track is only able to take trains running at 40mph, down from 80mph.

"We're very grateful for everyone's patience as we know the changes to trains must be frustrating, but the changes are there to keep everyone safe."